Medication delivery device

ABSTRACT

The present invention relates to a medication delivery device, to dosing mechanisms suitable for use in medication delivery devices, in particular in pen-type injectors, preferably having dose setting means and a drive device enabling the administration of a medicinal product from a single- or multi-dose medication cartridge, to a use of such device, and to a method of manufacturing or assembling such device.

The present invention relates to a medication delivery device, a use ofthe device and a method of manufacturing or assembling the device.

The invention refers particularly to dosing mechanisms suitable for usein medication delivery devices, in particular in pen-type injectors,preferably having dose setting means and a drive device enabling theadministration of a medicinal product from a single- or multi-dosemedication cartridge. In particular, the present invention relates tosuch medication delivery devices where a user may set a dose ofmedication to be delivered from a multi-dose cartridge. Most preferably,the medication delivery device comprises a single- or multi-dosemedication cartridge which can be replaced when the medication has beenfully dispensed.

The present invention further relates to a reset mechanism for amedication delivery device, and particularly to a reset mechanismcomprising a reset element which is engaged with a piston rod of themedication delivery device. Most preferably the reset mechanismaccording to the preset invention is activated and deactivated by amedication receptacle being engaged with and disengaged from the housingof the medication delivery device, respectively.

Such medication delivery devices have application where regularinjections by persons without formal medical training occur, i.e.,patients. This is increasingly common amongst those having diabeteswhere self-treatment enables such persons to conduct effectivemanagement of their diabetes.

These circumstances set a number of requirements for medication deliverydevices of this kind. The device must be robust in construction, yeteasy to use in terms of the manipulation of the parts, understanding bya user of its operation and the delivery of the required dose ofmedicament. Dose setting must be easy and unambiguous. In the case ofthose with diabetes, many users will be physically infirm and may alsohave impaired vision requiring the dosing mechanism to have a drivedevice which requires a low dispensing force and the medication deliverydevice to have an easy to read dose setting display.

As a result of environmental and economical reasons this kind ofmedication delivery device has been developed to allow only a part ofthe device to be discarded after all the medicament has been delivered,usually the medication cartridge only. This provides the additionalrequirement for such a medication delivery device that the resetting ofthe drive mechanism, when a new cartridge is attached to or insertedinto the medication delivery device, needs to be easy and unambiguouswithout the need for the user to touch any component of the drivemechanism directly, thereby reducing the possibility of damage to thedrive mechanism through e.g. contamination.

A further requirement of such reusable devices is that when a newcartridge is attached there should be no movement of the bung in thecartridge and thus no pressurisation of the contents of the cartridgeprior to dose setting and dose delivery. If this occurs, the accuracy ofthe device could be affected.

User operated medication delivery devices are well known within themedical field.

WO 2004/078239 A1 discloses a drive mechanism for a drug delivery devicewith a housing having a helical thread, a dose dial sleeve having ahelical thread engaged with the helical thread of the housing, a drivesleeve releasably connected to the dose dial sleeve and a clutch meanslocated between the dose dial sleeve and the drive sleeve. When the dosedial sleeve and the drive sleeve are coupled via the clutch means, bothare allowed to rotate with respect to the housing. When the dose dialsleeve and the drive sleeve are decoupled, rotation of the dose dialsleeve with respect to the housing is allowed whilst rotation of thedrive sleeve with respect to the housing is not allowed, whereby axialmovement of the drive sleeve is allowed so that a force is transferredin the longitudinal direction to a piston rod for medication delivery.This document neither describes the replacement of the cartridge, nor aresetting of the drive mechanism.

The following prior art documents address the reusability of suchdevices using a disposable and replaceable medicament cartridge that isattachable to/detachable from a reusable (resettable) drive mechanism.

In EP 0 554 996 B1 discloses an injection device comprising a housingand means for mounting a fluid containing cartridge containing aninternal piston to the housing. A lead screw is movably mounted withinthe housing and a dose setting means is provided for selecting theamount of fluid to be delivered by the device. This device provides asolution for changing the cartridge and resetting the dosing mechanismof the reusable injection device. The new cartridge is inserted into thehousing which is then screwed into place while the piston of thecartridge pushes the lead screw into the device which may have thedisadvantage of applying pressure to the piston at the end of thescrewing.

U.S. Pat. No. 5,827,232 teaches a medication delivery pen, comprising adisposable medication containing cartridge assembly. The cartridgeassembly comprises a cartridge with a pierceably sealed distal end and aplunger in sliding fluid tight engagement therein to dispense medicationfrom the cartridge when the plunger slides in a distal direction.Furthermore, the medication delivery pen comprises a reusable pen bodyassembly which has a housing, a lead screw disposed in the housing and adriver means for moving the lead screw distally in the pen body assemblyselected amounts. Whilst this device provides a solution for resetting amedication delivery pen drive mechanism it does require the user toalign the cartridge holder with slots at the distal end of the pistonrod which may be difficult for users with impaired eyesight and/orimpaired dexterity.

WO 1997/010864 A1 describes a medication delivery pen comprising acartridge holder assembly for holding a cartridge having a plunger, thecartridge holder assembly having a plurality of threads at a proximalend. A pen body assembly comprises a plurality of threads at a distalend for threading with the threads in the cartridge holder assembly. Alead screw extends form the distal end for engaging the plunger in thecartridge. Means for driving the lead screw into the cartridge areprovided to move the plunger in the distal direction. Furthermore, meansfor disengaging the driving means from the lead screw are provided topermit the lead screw to automatically and easily retract into the penbody when the pen body assembly approaches and is being threaded to thecartridge holder assembly. However, the disclosed solution for mountinga new cartridge holder assembly to the reusable pen body assembly mayhave the disadvantage of applying pressure to the plunger at the end ofthe assembling.

The object of the invention is avoid the disadvantages of knownmedication delivery devices, particularly to provide a flexible resetmechanism for use in a medication delivery device by means of which themedication delivery device can be reset for re-use when the medicationcartridge is replaced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a to 1 c show a cross-sectional view of one embodiment of amedication delivery device according to the invention in three differentstates;

FIGS. 2 a to 2 c show schematically an embodiment of an actuation meansinteracting with locking means in three different states according toone embodiment of the present invention;

FIG. 3 shows a cross-sectional enlarged view of a middle part of theembodiment according to FIGS. 1 a to 1 c showing the reset element ofthe medication delivery device in the operational state,

FIG. 4 shows schematically a different embodiment of the medicationdelivery device according to the present invention with a differentarrangement of actuation means, locking means and reset element and

FIG. 5 shows another embodiment of a medication delivery deviceaccording to the invention.

The medication delivery device according to the present inventionprovides a valuable technical alternative for known medication deliverydevices. The medication delivery device according to the presentinvention e.g. has the advantage that the piston rod is driven back intothe device body when a new cartridge is attached, without the userhaving to touch any part of the dosing mechanism and without anymovement of the cartridge bung. The medication delivery device accordingto instant invention further provides the advantage of an easyreplacement of the medication cartridge almost without application ofpressure on the bung of the cartridge during resetting of the device andtherefore without pressurization of the medication within the cartridgebefore the first setting and dispensing of a dose.

According to the invention, a medication delivery device is provided,comprising:

-   -   a housing having a proximal and a distal end,    -   a medication receptacle designed to be engaged with the housing    -   a piston rod which is movable in a distal direction for        medication delivery and    -   a drive device for rotating the piston rod in a first rotational        direction and thereby moving the piston rod in the distal        direction for medication delivery.

The piston rod comprises two threaded sections, wherein a first threadedsection is provided for threaded engagement with a reset element and asecond threaded section is provided for threaded engagement with thedrive device and the threads in the first and second threaded sectionsare oppositely disposed.

In an operational state the reset element is prevented from rotationwith respect to the housing, the piston rod being prevented from movingin a proximal direction. In a resetting state the reset element isallowed to rotate with respect to the housing, the medication deliverydevice being resettable by rotating the piston rod and the reset elementin a second rotational direction and moving the piston rod in theproximal direction.

The medication delivery device according to the present invention isdesigned such that, in the operational state the piston rod can be movedaxially in the distal direction and rotated in one direction (the firstrotational direction) with respect to the housing by the drive devicefor medication delivery and the piston rod is prevented from axialmovement in the proximal direction with respect to the housing.

According to the present invention the medication delivery device isdesigned such that in the operational state, the reset element isprevented from rotation with respect to the housing. Preferably, thereset element is prevented from any movement (translational as well asrotational movement) with respect to the housing in the operationalstate. Preferably, the reset element is mounted within the housing suchthat it is prevented from axial movement with respect to the housing atany time and it is additionally prevented from rotation only in theoperational state. Alternatively, the reset element can be mountedwithin the housing such that it is retained for rotational movement andfor limited axial movement with respect to the housing in the resettingstate and it is prevented from axial movement and from rotation withrespect to the housing in the operational state.

Furthermore, the medication delivery device is designed such that in theresetting state, the piston rod is free to move axially in the proximaldirection with respect to the housing (while rotating in the otherdirection—the second rotational direction). Preferably, the medicationdelivery device is designed such that in the resetting state, the pistonrod is free to be wound back in the proximal direction with respect tothe housing e.g. for resetting the piston rod when a new medicationreceptacle (e.g. a new cartridge or a cartridge holder with a newcartridge) is mounted on the distal end of the housing of the device.

According to a preferred embodiment of the present invention themedication delivery device is designed such that

-   -   when the medication receptacle is engaged with the distal end of        the housing the reset element is in the operational state and    -   when the medication receptacle is disengaged from the distal end        of the housing the reset element is in the resetting state.

According to this embodiment, the movement for engaging the medicationreceptacle with the housing results in the reset element being movedinto a position or brought into a state in which it is rotatably lockedwith respect to the housing. This can be achieved e.g. by moving thereset element into a position in which it engages with features (e.g.with teeth or splines) of the housing or of another non-rotatablecomponent of the medication delivery device or e.g. by moving anothernon-rotatable component into a position in which it engages with thereset element and prevents rotation thereof.

The present invention therefore further refers to a medication deliverydevice comprising:

-   -   a housing having a proximal and a distal end,    -   a medication receptacle designed to be engaged with the distal        end of the housing    -   a piston rod which is movable in a distal direction for        medication delivery and    -   a drive device for rotating the piston rod in a first rotational        direction and thereby moving the piston rod in the distal        direction for medication delivery.

The piston rod is threadedly engaged with a reset element. Preferably,the piston rod comprises two threaded sections, wherein a first threadedsection is provided for threaded engagement with the reset element and asecond threaded section is provided for threaded engagement with thedrive device and the threads in the first and second threaded sectionsare oppositely disposed.

When the medication receptacle is engaged with the housing the resetelement is prevented from rotation with respect to the housing, thepiston rod thereby being prevented from moving in a proximal direction.When the medication receptacle is disengaged from the housing the resetelement is allowed to rotate with respect to the housing, the medicationdelivery device being resettable by rotating the piston rod and thereset element in a second rotational direction and moving the piston rodin the proximal direction. The device is therefore in an operationalstate when the medication receptacle is engaged with the housing and ina resetting state when the medication receptacle is disengaged from thehousing.

According to a preferred embodiment of the present invention themedication receptacle is designed to be engaged with the distal end ofthe housing by engagement of first engagement means and secondengagement means. The first engagement means and the second engagementmeans are movable into engagement e.g. by a movement of the medicationreceptacle which comprises a rotational movement without axial movementof the medication receptacle (e.g. a movement which ends in a rotationalmovement without axial movement of the medication receptacle) withrespect to the housing (or vice versa, by a movement of the housingwhich comprises a rotational movement without axial movement of thehousing (e.g. a movement which ends in a rotational movement withoutaxial movement of the housing) with respect to the medicationreceptacle). The reset element can thus preferably be brought into theoperational state during a rotational movement of the medicationreceptacle while the medication receptacle does not move axially withrespect to the housing or during a rotational movement of the housingwhile the housing does not move axially with respect to the medicationreceptacle.

However, the medication receptacle can be engaged with the housing byany engagement means known by those skilled in the art.

The medication receptacle of the medication delivery device can comprisean actuation means for bringing (and preferably also for holding) thereset element in an operational state in which the reset elementpreferably guides the piston rod for medication delivery. The housingand the medication receptacle can be movable into engagement e.g. by amovement which comprises, preferably ends in a rotational movementwithout axial movement of the actuation means with respect to thehousing, the actuation means thereby bringing the reset element in theoperational state.

The medication delivery device can be designed such that, by a movement,e.g. a rotational movement, of the actuation means, the actuation meansis directly or indirectly interacting with the reset element forbringing the same in the operational state and thereby bringing themedication delivery device in an operational state for medicationdelivery in which the reset element is prevented from rotating withrespect to the housing and in which the piston rod is prevented frommoving in the proximal direction.

In a preferred embodiment of the present invention first and secondengagement means of the housing and the medication receptacle aredesigned such that when the medication receptacle and the housing aremoved into engagement the actuation means are first rotated and movedaxially with respect to the housing and are thereafter rotated withoutbeing moved axially, thereby bringing the reset element in theoperational state. When the first and second engagement means are movedout of engagement (and thus when the medication receptacle is disengagedfrom the housing), the reset element preferably moves out of or isbrought out of the operational state into another position (resettingstate) in which it no longer guides or holds the piston rod.

According to a preferred embodiment of the present invention themedication receptacle or an insert of the medication receptaclecomprises the first engagement means and the housing or an insert of thehousing comprises the second engagement means.

The first engagement means can e.g. be a thread of the medicationreceptacle (preferably an external thread) and the second engagementmeans an engaging element of the housing or of an insert of the housingfor engagement with the thread of the medication receptacle, wherein thedistal end of the thread of the medication receptacle merges into anannular groove such that the medication receptacle is engaged with thehousing by first rotating and moving proximally with respect to thehousing and then only rotating with respect to the housing. The purerotation at the end of the engaging movement is caused by the engagingelement moving along the annular groove which does not have a pitch(i.e. the lead of which is zero). Preferably the annular groove is onlya part annular groove which runs around a part (e.g. ⅙) of the perimeterof an essentially tubular end of the medication receptacle.Alternatively, the thread/annular groove can be part of the housing andthe medication receptacle can comprise the engaging element.

Alternatively, the distal end of the housing can e.g. be provided withan insert comprising the second engagement means and designed to engagewith the first engagement means at the proximal end of the medicationreceptacle, the insert being secured against rotation but being free tomove axially with respect to the housing (limited axial movement),wherein distal axial movement of the insert is limited by a retainingmeans. Particularly, the insert of the housing can comprise an innerthread as a second engagement means for engaging a first engagementmeans which is an outer thread at the proximal end of the medicationreceptacle, the medication receptacle comprising the actuation means andbeing rotated and moved axially with respect to the insert and thehousing in a first step for engaging the medication receptacle with thehousing and the medication receptacle being rotated while axial movementof the medication receptacle is prevented with respect to the housing ina second step for engaging the medication receptacle with the housing,the insert being moved in the distal direction by the rotation of themedication receptacle during the second step. The insert can be moved inthe distal direction e.g. until the insert abuts the retaining means oruntil the inner thread of the insert ends.

According to a preferred embodiment of the present invention the insertis a movable sleeve with an internal thread and the retaining member isa retaining ring which limits the distal axial movement of the sleeve.The retaining ring is attached to the distal end of the housing suchthat it is prevented from rotation and from axial movement with respectto the housing. Furthermore, a spring member is provided to move thesleeve against a proximal axial stop means (e.g. an annular rib) withinthe housing when the medication receptacle is not engaged with thehousing of the device. The spring member preferably abuts the proximalside of the retaining ring on one side and the distal side of themovable sleeve on the other side. The sleeve is engaged with the housingsuch that it is allowed to move linearly and restrained from rotation.When the housing and the medication receptacle are moved intoengagement, an external thread on the proximal end of the medicationreceptacle engages the internal thread of the sleeve. Therefore themedication receptacle is screwed into the distal end of the housing,until the proximal edge or shoulder of the medication receptacle abutsthe distal side of the retaining ring. This abutment prevents a furtherlinear proximal movement of the medication receptacle. However, afurther rotation of the medication receptacle is allowed, therebycausing the sleeve to move linearly in the distal direction against theforce of the spring means until the sleeve abuts the proximal side ofthe retaining ring. This abutment ends the engaging movement of thehousing and the medication receptacle. The pure rotation of themedication receptacle at the end of the engaging movement is used tobring a reset element into its operational state in which it guides thepiston rod for medication delivery.

In all of the embodiments of the present invention, the reset element ispreferably a nut means which is threadedly engaged with the piston rod,preferably with an external thread of the piston rod. According to apreferred embodiment of the present invention the reset element is a nutmeans which is threadedly engaged with the piston rod and which isengaged with a locking means in the operational state and which isdisengaged from the locking means in the resetting state.

According to a preferred embodiment of the present invention the drivedevice comprises a drive sleeve and a second threaded section of thepiston rod is provided for threaded engagement with the drive sleeve.

In this embodiment, the medication delivery device can be designed suchthat the drive sleeve is threadedly engaged with (the second threadedsection of) the piston rod and when the drive sleeve drives the pistonrod in distal direction for medication delivery, the drive sleeve ismoved axially and is prevented from rotation with respect to thehousing, thereby causing axial distal movement and rotation of thepiston rod. The displacement of the drive sleeve in the distal direction(without rotating) with respect to the housing during medicationdelivery results in a displacement of the drive sleeve in the distaldirection with respect to the piston rod. This displacement causes thepiston rod to rotate in the first rotational direction due to thethreaded engagement of the drive sleeve with the second threaded sectionof the piston rod. This rotational movement of the piston rod winds thepiston rod in the distal direction due to the threaded engagement of thereset element with the first threaded section of the piston rod. Thepiston rod therefore pushes a piston within the medication receptacle inthe distal direction, thereby delivering medication out of themedication receptacle.

A mechanical advantage can be achieved e.g. if the thread of the secondthreaded section (which is engaged with the drive device, preferablywith the drive sleeve) has a larger pitch than the thread of the firstthreaded section (which is engaged with the reset element). Therefore,according to a preferred embodiment of the present invention the pistonrod has a thread in the first threaded section with a first pitch and athread in the second threaded section with a second pitch, wherein thefirst pitch is smaller than the second pitch (the lead of the thread inthe first threaded section being smaller that the lead of the thread inthe second threaded section).

Preferably, the medication delivery device according to the presentinvention further comprises stop means, the stop means being designedsuch that

-   -   during dose setting the drive sleeve is not allowed to move        axially without rotation with respect to the housing and    -   during dose delivery rotation of the drive sleeve with respect        to the housing is not allowed while the drive sleeve is allowed        to move axially in the distal direction with respect to the        housing.

The stop means can e.g. comprise a clutch means which is non-rotatablyengaged with the drive sleeve. Preferably, the clutch means is locatedbetween a dose dial sleeve and the drive sleeve and is provided tocouple and decouple the dose dial sleeve and the drive sleeve.

The medication delivery device according to the present inventionpreferably comprises a dosing mechanism which includes the piston rodand the drive device. Further, the dosing mechanism can comprise:

-   -   a dose dial sleeve having a helical thread engaged with a        helical thread of the housing, the drive sleeve being releasably        coupled with the dose dial sleeve and    -   a clutch means located between the dose dial sleeve and the        drive sleeve, wherein,

-   a) when the dose dial sleeve and the drive sleeve are coupled (by    means of the clutch means), both are allowed to rotate with respect    to the housing, and

-   b) when the dose dial sleeve and the drive sleeve are de-coupled,    rotation of the dose dial sleeve with respect to the housing is    allowed, whilst rotation of the drive sleeve with respect to the    housing is not allowed and axial movement of the drive sleeve is    allowed in the distal direction thereby transferring a force in the    distal direction to the piston rod.

Preferably, when the dose dial sleeve and the drive sleeve are coupled(by means of the clutch means), both are allowed to rotate and moveaxially with respect to the housing whilst both are not allowed to moveaxially without rotating with respect to the housing (e.g. by the dosedial sleeve being engaged with the housing via a helical thread).According to a preferred embodiment of the present invention, the dosedial sleeve and the drive sleeve are coupled during dose setting anddecoupled during dose delivery.

The dose dial sleeve and the drive sleeve are preferably coupled duringresetting of the medication delivery device (in the resetting state).Preferably, in the resetting state the drive sleeve is not allowed tomove axially. Alternatively and most preferably, in the resetting statethe drive sleeve is only allowed to move axially in combination with arotational movement (e.g. the drive sleeve being indirectly coupled to athread of the housing via a clutch means and a dose dial sleeve) and notallowed to move axially without rotating. Consequently in the resettingstate, when a force is applied (e.g. by a user) to push the distal endof the piston rod (e.g. a pressure foot) in the proximal direction, thepiston rod rotates together with the reset element in the secondrotational direction. The piston rod is thereby wound in the proximaldirection by means of the threaded engagement between the drive sleeveand the second threaded section while the drive sleeve does not moveaxially.

According to a preferred embodiment of the present invention the pitch(and lead) of the helical thread of the dose dial sleeve which isengaged with the helical thread of the housing is the same as the pitch(and lead) of the thread in the second threaded section of the pistonrod. In this case the displacement of the dose dial sleeve with respectto the housing is identical to the displacement of the drive sleeve withrespect to the piston rod during dose setting.

In all above mentioned embodiments, the medication delivery device cancomprise a locking means which is non-rotatable with respect to thehousing and which is engageable with the reset element, thereby lockingthe reset element for preventing rotation of the reset element withrespect to the housing in the operational state. Preferably, the lockingmeans is splined to the housing or to an insert of the housing, therebybeing allowed to move axially but being prevented from rotating withrespect to the housing. Preferably, the locking means is allowed to moveaxially only for a limited axial movement with respect to the housing.Alternatively, the locking means can be fixed to the housing or even bepart of the housing and therefore be prevented from any movement withrespect to the housing.

When the reset element is engaged with a locking means in theoperational state, the piston rod is preferably prevented from rotationin one rotational direction and from axial movement in the proximaldirection with respect to the housing but is allowed to rotate in theother rotational direction and to move axially in the distal directionwith respect to the housing for medication delivery.

The reset element or the locking means of the medication delivery deviceaccording to the present invention can comprise a shape which interactswith the shape of an actuation means for driving the locking means andthe reset element into engagement by a rotational movement (preferablywithout an axial movement) of the actuation means with respect to thehousing.

Particularly, at least one inclined surface can be arranged on theactuation means and at least one correspondingly inclined surface can bearranged on the reset element or on the locking means, wherein theinclined surfaces are formed such that for interaction of the actuationmeans and the reset element or of the actuation means and the lockingmeans the inclined surfaces can glide along each other.

Preferably, the actuation means comprises at least one protrusion withthe inclined surface fixedly or movably arranged on the actuation meansor it comprises at least one ramp with an inclined surface forinteracting with the reset element or the locking means e.g. by arotational movement of the actuation means in one direction with respectto the housing, thereby driving the reset element and the locking meansinto engagement.

The locking means and the reset element can e.g. comprise face teethwhich interlock when the locking means and the reset element are engagedin the operational state. In the resetting state, the face teeth aredisengaged and the locking means and the reset means are thereforedisengaged.

Further, the medication delivery device is preferably designed such thatthe locking means disengages from the reset element under the force of abiasing means e.g. when the medication receptacle is disengaged from thehousing. The biasing means is preferably a spring which forces the resetelement and the locking means apart when the medication receptacle isseparated from the housing of the medication delivery device. Mostpreferably the biasing means moves the locking means axially away fromthe reset element when the medication receptacle is disengaged from thedistal end of the housing, thereby disengaging the locking means and thereset element.

Additionally or alternatively, the medication delivery device can bedesigned such that when the medication receptacle is disengaged from thehousing, the locking means is disengaged from the reset element, wherebythe reset element is free to rotate with respect to the housing. Whenthe locking means and the reset element are disengaged in thisembodiment, the reset element is no longer in the operational state, butin the resetting state. According to a preferred embodiment of thepresent invention the piston rod is free to move proximally when thelocking means is disengaged from the reset element.

Preferably, the medication receptacle is a cartridge holder which isdesigned to receive a cartridge filled with medication. The cartridgeholder is designed to be engaged with a distal end of the housing.Alternatively the medication receptacle can e.g. be a cartridge havingfirst engagement means for engaging second engagement means of thehousing. A cartridge filled with medication is preferably a tubularsleeve containing the medication and being closed by a piston at one endand by a piercable septum at the other end. When the piston is movedproximally in the cartridge, the medication is dispensed e.g. through aneedle which protrudes through the septum and which is in communicationwith the medication (e.g. insulin).

According to a preferred embodiment of the present invention themedication receptacle (or an insert or attachment of the medicationreceptacle) and the housing (or an insert or attachment of the housing)can additionally be provided with snap-in features by means of which themedication receptacle and the housing are held in engagement duringnormal use of the medication delivery device, especially during dosesetting and medication delivery. Furthermore the snap-in features canprovide an audible and/or tactile feedback to the user, when themedication receptacle is safely attached to the housing.

The medication delivery device can be a pen-type device and/or aninjector-type device. The medication delivery device can comprise aneedle or be a needle-free device.

The term “medication delivery device” according to instant inventionshall mean a single-dose or multi-dose, disposable or re-usable devicedesigned to dispense a dose of a medicinal product, preferably multipleselected doses, e.g. of insulin, growth hormones, low molecular weightheparins, and their analogues and/or derivatives etc. Said device may beof any shape, e.g. compact or pen-type. Dose delivery may be providedthrough a mechanical (optionally manual) dosing mechanism or electricaldosing mechanism or electro-mechanical dosing mechanism or stored energydosing mechanism, such as a spring, etc. Dose selection may be providedthrough a manual mechanism or electronic mechanism or electro-mechanicalmechanism. Additionally, said device may contain components designed tomonitor physiological properties such as blood glucose levels, etc.Furthermore, the said device may comprise a needle or may beneedle-free. Preferably, the term “medication delivery device” shallmean a re-usable multi-dose pen-type device having mechanical and manualdose selection and dose delivery mechanisms, which is designed forregular use by persons without formal medical training such as patients.Preferably, the medication delivery device is of the injector-type. Mostpreferably the medication delivery device is designed to deliver a fluidmedication.

The term “medication receptacle” in the context of the present inventionshall preferably mean a cartridge containing a medication or a cartridgeassembly, most preferably a cartridge holder for receiving a cartridgecontaining a medication. Furthermore, the terms “medication receptacle”and “cartridge” and “cartridge assembly” are exchangeable in the contextof the present invention. This means that by using the term “medicationreceptacle”, any meaning of the terms “cartridge” or “cartridgeassembly” is included, and vice versa.

The term “cartridge holder” according to instant invention shall meanany component and/or components designed to house a medicament cartridgecontaining a medication to be delivered by the medication deliverydevice. Said cartridge holder may be of any shape, e.g. cylindricaland/or tubular. In general, the cartridge holder may be unitary or amultipart component of a cylindrical tubular or non-tubular shape. Itmay be made of any suitable material known by a person skilled in theart, e.g. of a transparent material. Further the cartridge holder or aninsert of the cartridge holder is preferably provided with engagementmeans, e.g. helical threads or part threads or bayonet or the like, onan external and/or internal surface of the distal end and/or proximalend of the cartridge holder or the insert designed for engagement withcorresponding engagement means located on an exterior and/or interiorsurface of a housing, an insert of the housing and/or a needle assembly.In a preferred embodiment the cartridge holder is of a unitary tubulardesign having an external thread located at its proximal end.

The term “housing” according to instant invention shall preferably meanany exterior housing (“housing”, “body”, “shell”) or interior housing(“insert”, “inner body”) having an engaging means, such as a helicalthread, spline or any other suitable means known by a person skilled inthe art. The housing may be designed to enable the safe, correct, andcomfortable handling of the medication delivery device or any of itsmechanisms. Usually, it is designed to engage with any of the innercomponents of the medication delivery device (e.g., a dosing mechanism,cartridge, plunger, piston rod), to house, fix, guide, and/or protect bylimiting the exposure to contaminants, such as liquid, dust, dirt etc.In general, the housing may be unitary or a multipart component oftubular or non-tubular shape. The exterior housing may also serve tohouse a cartridge from which a number of doses of a medicinal productmay be dispensed.

The term “reset element” according to the present invention shallpreferably mean any component designed to prevent the resetting of themedication delivery device when the reset element and therefore themedication delivery device are in the operational state and designed toenable the resetting of the medication delivery device when the resetelement and therefore the medication delivery device are in theresetting state. The reset element can therefore assume a resettingstate and an operational state. The reset element preferably also hasthe function of guiding the piston rod in the operational state duringmedication delivery. For this guiding function of the reset elementpreferably comprises a shape for interacting with a corresponding shapeof the piston rod, e.g. an inner thread for engaging an outer thread ofthe piston rod or a non circular opening for holding a piston rod with acorresponding non-circular form or a piston rod with a section havingthe corresponding non-circular form.

The term “operational state” according to the present invention shallpreferably mean a position or state of the reset element in which thereset element prevents the resetting of the medication delivery device,i.e. it directly or indirectly prevents a movement of the piston rod inthe proximal direction. Preferably, the operational state is furthermorea position or state of the reset element in which the reset elementguides and/or holds the piston rod. The reset element and therefore themedication delivery device are preferably in the operational state whenthe medication delivery device is used for dose setting and medicationdelivery.

The term “resetting state” according to the present invention shallpreferably mean a position or state of the reset element in which thereset element allows the resetting of the medication delivery device,i.e. it directly or indirectly allows a movement of the piston rod inthe proximal direction. The reset element is preferably in the resettingstate when the medication delivery device is disassembled (i.e. themedication receptacle disengaged from the housing) for replacing anempty cartridge by a new cartridge filled with medication.

The term “nut means” according to instant invention shall preferablymean any component designed to be threadedly engaged with a piston rod,preferably to act as a guide for the piston rod. Further, the term “nutmeans” according to instant invention shall mean any component with athreaded circular opening that may be a single or multiple partcomponent. According to a preferred embodiment of the present invention,the reset element is a nut means. In a further more specific embodimentthe nut means is free to rotate with respect to the housing when notengaged with a locking means of the medication delivery device.According to one embodiment of the present invention, the nut means isfree to rotate with respect to the housing and is secured against linearaxial movement with respect to the housing when not engaged with alocking means of the medication delivery device, but is secured againstrotation and linear axial movement with respect to the housing whenengaged with the locking means. Most preferably, the nut means is freeto rotate and retained for limited linear axial movement with respect tothe housing when not engaged with a locking means of the medicationdelivery device, but is secured against rotation and linear axialmovement with respect to the housing when engaged with the lockingmeans. In an even more specific embodiment the nut means has a texturedsurface, for example a set of face teeth (saw teeth, dog teeth, crownteeth, or the like) or any other suitable frictional face, preferably toengage a textured surface of another component of the device, mostpreferably of a locking means.

The term “locking means” according to instant invention shall preferablymean any component that is part of the housing, fixed to the housing orengaged with the housing or with an insert of the housing such that itis prevented from rotational movement with respect to the housing, mostpreferably such that it is allowed to move longitudinally but isprevented from rotational movement with respect to the housing. In apreferred embodiment the locking means has a textured surface, forexample a set of face teeth (saw teeth, dog teeth, crown teeth, or thelike) or any other suitable frictional face. In a more preferredembodiment a non-rotatable locking means is designed to engage with thereset element, thereby preventing rotation of the reset element withrespect to the housing. In a more specific preferred embodiment ofinstant invention, a textured surface of the non-rotatable locking meansengages with a textured surface of a reset element (preferably a nutmeans) in the operational state to prevent the reset element fromrotating as long as a medication receptacle (preferably a cartridgeholder) is engaged with the housing.

The term “actuation means” according to instant invention shallpreferably mean any component of the medication delivery device and/orpart of a component of the medication delivery device designed to moveany other component(s) of the medication delivery device into and/or outof engagement with another component of the medication delivery deviceand/or components of the medication delivery device and/or to maintainany component(s) of the medication delivery device in engagement.Preferably the actuation means is a means to actuate a locking means inorder to move the locking means into engagement with the reset element.Alternatively the actuation means can be a means to actuate the resetelement in order to move the reset means into engagement with a lockingmeans. In a preferred embodiment of instant invention, the actuationmeans shall form an integral part of the proximal end of the medicationreceptacle, e.g. the cartridge holder of the medication delivery device.

The term “stop means” according to instant invention shall mean anyfeature(s) and/or component(s) of the medication delivery devicedesigned to prevent axial and/or rotational movement of any componentand/or components at least in one direction. In a preferred embodimentof instant invention, the term “stop means” shall mean any featureperpendicular to the distal-proximal axis of the medication deliverydevice (particularly any planar surface feature perpendicular to thedistal-proximal axis of the medication delivery device) designed toprevent axial movement of a component in one direction when thiscomponent abuts the perpendicular feature. According to anotherpreferred embodiment of the present invention the term “stop means”shall mean any feature which provides a radial or rotational stopdesigned to prevent rotational movement of a component in one rotationaldirection when an abutment element of the component abuts the radial orrotational stop feature.

In still a further preferred embodiment of instant invention, the term“stop means” shall mean a component (“end stop”) of the dosing mechanismwhich prevents the setting of a dose which exceeds the amount ofmedication left in the medication receptacle. Preferably the end stop isa component which is secured against rotation but allowed to moveaxially with respect to a housing and which shall prevent at least onecomponent of the dosing mechanism from rotational and/or axial movementwhen a final dose has been set, thereby preventing the setting of a dosewhich exceeds the amount of medication left in the cartridge.Furthermore, the “end stop” shall preferably have a helical thread on anexterior surface designed to engage with an interior helical thread of adose dial sleeve of the dosing mechanism or of an insert of a dose dialsleeve of the dosing mechanism. Preferably the lead of an externalhelical thread of the said dose dial sleeve for threaded engagement withthe housing shall be greater than the lead of the internal helicalthread of the dose dial sleeve for threaded engagement of the said endstop.

The term “engaging” according to instant invention shall mean theinterlocking of two or more components of the dosingmechanism/medication delivery device, by means of e.g. a spline, thread,or meshed teeth connection, preferably the interlocking of threads ofcomponents (“threadedly engaged”).

The term “engagement means” according to the present invention shallpreferably mean any means known to those skilled in the art which can beused to engage two or more components of a medication delivery device,e.g. full or part threads, grooves, engaging elements which mesh withthreads and/or grooves or means which form a bayonet lock.

The term “disengaging” according to instant invention shall mean theunlocking of two or more components of the dosing mechanism/medicationdelivery device. According to one example the term “disengaging”according to instant invention shall mean the unlocking of two or morecomponents of the dosing mechanism/medication delivery device under theforce of a biasing means. Two components can also be disengaged by theforce of a user of the device, e.g. by a patient unscrewing themedication receptacle from the housing.

The term “biasing means” according to instant invention shall preferablymean any component that is provided for exerting a force on a componentand/or components to ensure that the component and/or components areforced together (e.g. into engagement) or forced apart (e.g. out ofengagement). Preferably the biasing means may be manufactured from anysuitable flexible energy storage material known by a person skilled inthe art (e.g. metal, rubber or plastics) and may take any suitable form,e.g., a spring. In a more preferred embodiment the biasing means is aspring component e.g. located between the reset element and the lockingmeans. In another preferred embodiment the biasing means is a springcomponent located between a nut means and a locking means and located inthe housing.

The term “distal end” according to instant invention shall mean the endof the device or a component of the device which is closest to thedispensing end of the device. Preferably a needle assembly is providedat the distal end of the medication delivery device of the presentinvention the needle of which can be inserted into the skin of a patientfor medication delivery.

The term “proximal end” according to instant invention shall mean theend of the device or a component of the device which is furthest awayfrom the dispensing end of the device. Preferably a button is providedat the proximal end of the medication delivery device of the presentinvention which is pushed for dose delivery.

The term “dosing mechanism” according to instant invention shall meanany component and/or components and/or assembly designed to allow a userto select and/or set a dose to be dispensed and/or to provide and/or totransmit a force necessary to dispense a dose of a medication. Saiddosing mechanism may be composed of mechanical and/or electro-mechanicaland/or electronic components. Additionally, the dosing mechanism may behoused by and/or engaged with the device housing or may be anindependent assembly. The dosing mechanism of instant inventioncomprises a piston rod and a drive device for moving the piston rod inthe distal direction for medication delivery. Preferably, the dosingmechanism of instant invention comprises a drive sleeve and a dose dialsleeve. More preferably, the dosing mechanism of instant inventioncomprises a drive sleeve, a dose dial sleeve, a clutch means, a dosedial grip and a button means.

The term “piston rod” according to instant invention shall mean acomponent adapted to operate through/within the housing, designed totranslate axial movement (preferably towards the distal end)through/within the medication delivery device, preferably from a drivesleeve to the piston of the cartridge, for the purpose ofdischarging/dispensing a medication from the cartridge, preferably aninjectable product. Said piston rod may be flexible or not. It may be asimple rod, a lead-screw, a part of a rack and pinion system, a part ofa worm gear system, or the like. The “piston rod” shall further mean acomponent having a circular or non-circular cross-section. It may bemade of any suitable material known by a person skilled in the art.

In a preferred embodiment, the piston rod comprises at least two, morepreferably two, external and/or internal helical threads (threadedsections). In another preferred embodiment of the piston rod accordingto instant invention, a first helical thread (first threaded section) islocated at a distal end and a second helical thread (second threadedsection) is located at a proximal end of the said piston rod, wherebythe said threads of the threaded sections have opposite dispositions. Inanother preferred embodiment the piston rod of instant inventioncomprises at least two threaded sections with threads having the sameleads and the same pitches at the distal and the proximal end. In yetanother preferred embodiment of instant invention the lead and the pitchof the second helical thread of the piston rod shall be greater than thelead and the pitch of the first helical thread. More preferred, theratio of the leads of the helical threads of the said first and thesecond helical threads is in the range of 1:1,01 to 1:20, even morepreferred in the range of 1:1,1 to 1:10, most preferred 1:2,3.Preferably, one of the said threads (the thread of the second threadedsection) is designed to engage with the drive sleeve. Preferably anotherof the said threads (the thread of the first threaded section) isdesigned to engage with the reset element, more preferably with a nutmeans. According to a most preferred embodiment of the presentinvention, a first external threaded section of the piston rod with athread having a smaller lead is designed to engage with an internalthread of a nut means and a second external threaded section of thepiston rod with a thread having a larger lead is designed to engage withan internal thread of a drive sleeve. In a further preferred embodimentof instant invention, the piston rod is provided with a stop meansdesigned to limit the proximal axial movement of an end stop. The stopmeans may e.g. be the start of one of the external threads of the pistonrod.

The term “dose dial sleeve” according to instant invention shallpreferably mean a component of the medication delivery device which isdirectly or indirectly used to select/dial a dose of medication to bedelivered. Additionally or alternatively the dose dial sleeve isdesigned to indicate a selected dose of a dispensable product(medication). This may be achieved by use of markings, symbols,numerals, etc., e.g. printed on the external surface of a sleeve or anodometer, or the like. Most preferably the dose dial sleeve is marked bymeans of laser printing. In a preferred embodiment of the presentinvention, the dose dial sleeve is an essentially tubular component ofessentially circular cross-section having either:

-   -   both an internal and external thread, or    -   an internal thread, or    -   an external thread.

Preferably, the dose dial sleeve comprises an external thread forengaging an internal thread of the housing or of an insert of thehousing. Preferably, the dose dial sleeve according to instant inventioncomprises an external helical thread having a lead, which is similar to,preferably the same as the lead of an internal helical thread of thedrive sleeve. In a more specific embodiment of instant invention, thedose dial sleeve is provided with a plurality of radially extendingmembers adapted to abut a corresponding plurality of radial stopsprovided within the housing or an insert of the housing. These radialstop means are preferably provided for stopping a further winding of thedose dial sleeve out of the housing when a dose is set and/or forstopping the further winding of the dose dial sleeve into the housingwhen a dose has been dispensed.

The term “drive device” according to the present invention shallpreferably mean any component and/or components and/or assembly designedto transmit a force to the piston rod for dispensing a dose of amedication. Said drive device may be composed of mechanical and/orelectro-mechanical and/or electronic components. The drive device may behoused by and/or engaged with the housing or may be an independentassembly. Preferably, the drive device of instant invention comprises adrive sleeve. More preferably, the drive device of instant inventioncomprises a drive sleeve, a clutch means and a button means.

The term “drive sleeve” according to instant invention shall preferablymean any component for directly or indirectly driving the piston rod ina distal direction for medication delivery, most preferably for drivingthe piston rod directly. According to a preferred embodiment of thepresent invention, the drive sleeve is an essentially tubular componentof essentially circular cross-section. In a preferred embodiment thedrive sleeve is engaged with the piston rod. Preferably the drive sleevecomprises an internal thread for engaging an external thread of thepiston rod. The drive sleeve is further preferably releasably coupled tothe dose dial sleeve, most preferably by a clutch means.

The term “thread” or “helical thread” according to instant inventionshall preferably mean a full or part thread, e.g., a cylindrical spiralrib/groove, located on the internal and/or external surface of acomponent of the medication delivery device, having an essentiallytriangular or square or rounded section designed to allow continuousfree rotational and axial movement between components. Optionally, athread may be further designed to prevent rotational or axial movementof certain components in one direction by being non-overhaulable.

The term “lead” according to instant invention shall preferably mean theaxial distance a nut would advance in one complete revolution;preferably “lead” shall mean the axial distance through which acomponent having a helical thread, i.e. dose dial sleeve, drive sleeve,piston rod, etc., of the dosing mechanism travels during one rotation.Therefore the lead is a function of the pitch of the thread of therelevant component.

The term “pitch” according to instant invention shall preferably meanthe distance between consecutive contours on a helical thread, measuredparallel to the axis of the helical thread.

One aspect of the present invention provides a medication deliverydevice according to instant invention for dispensing a medicinal productpreferably for dispensing a pharmaceutical formulation (e.g. solution,suspension etc.) comprising an active compound selected from the groupconsisting of insulin, growth hormone, low molecular weight heparin,their analogues and their derivatives.

The invention further refers to a method of manufacturing or assemblinga medication delivery device according to one of the above-mentionedembodiments. This method preferably comprises the step of moving amedication receptacle into engagement with the distal end of the housingof the device by engaging first engagement means with second engagementmeans. The engaging action of the medication receptacle being engagedwith the housing results in the reset element being brought in theoperational state in which the reset element is prevented from rotatingwith respect to the housing and in which the reset element thereforeprevents the proximal movement of the piston rod and consequently theresetting of the medication delivery device.

According to the invention, the use of a medication delivery deviceaccording to one of the above-mentioned embodiments of a medicationdelivery device for dispensing a medicinal product is also provided. Theuse preferably comprises the dispensing of a pharmaceutical formulation(e.g. a liquid medication like a solution, a suspension etc.) comprisingan active compound selected from the group consisting of insulin, growthhormone, low molecular weight heparin, their analogues, and theirderivatives.

Without any limitation, the present invention will be explained ingreater detail below with reference to the drawings in which:

-   -   FIGS. 1 a to 1 c show a cross-sectional view of one embodiment        of a medication delivery device according to the invention in        three different states;    -   FIGS. 2 a to 2 c show schematically an embodiment of an        actuation means interacting with locking means in three        different states according to one embodiment of the present        invention;    -   FIG. 3 shows a cross-sectional enlarged view of a middle part of        the embodiment according to FIGS. 1 a to 1 c showing the reset        element of the medication delivery device in the operational        state,    -   FIG. 4 shows schematically a different embodiment of the        medication delivery device according to the present invention        with a different arrangement of actuation means, locking means        and reset element and    -   FIG. 5 shows another embodiment of a medication delivery device        according to the invention.

Referring first to FIGS. 1 a to 1 c, there is shown a medicationdelivery device in accordance with the present invention in threedifferent positions.

The medication delivery device 1 comprises a cartridge holder 2 and a(exterior) housing 3. Preferably the housing 3 is lacquered. The distalend of the housing 3 is provided with an insert 3A which is immovablyattached to the housing. The insert 3A is provided with secondengagement means 4 for engaging first engagement means 5 of thecartridge holder 2. In the illustrated embodiment the insert 3A of thehousing 3 is provided with a series of part threads formed on aninterior surface of the insert 3A. The proximal end of the cartridgeholder 2 is provided with first engagement means 5 for engaging thesecond engagement means 4 of the insert 3A. In the illustratedembodiment the cartridge holder 2 is provided with a thread, the distalend of which merges into a (part) annular groove (not shown) formed onan exterior surface of the cartridge holder 2. The cartridge holder 2 issecured within the distal end of the housing 3 by the engagement of thesecond engagement means 4 of the insert 3A of the housing 3 with thefirst engagement means 5 of the cartridge holder 2. In the shownpreferred embodiment of present invention, the proximal end of thecartridge holder 2 is further provided with an actuation means 70designed to activate and lock a reset element (nut means 11) in anoperational state (described below and shown in FIG. 3).

A cartridge 6 from which a number of doses of a medicinal product may bedispensed is provided in the cartridge holder 2. A piston 7 is retainedin the cartridge 6.

A removable cap (not shown) can be releasably retained over the distalend of the cartridge holder 2. Preferably the cap comprises a clip whichis snapped onto the cap. The cap can also be lacquered.

The distal end of the cartridge holder 2 is provided with suitableengaging means 8, such as a helical thread, bayonet or the like, forengagement with a suitable needle assembly (not shown) to enablemedicament to be dispensed from the cartridge 6 and injected.

The medication delivery device 1 according to FIGS. 1 a to 1 c comprisesa dosing mechanism which includes a piston rod 17. The piston rod 17 isof generally circular cross-section. A pressure foot 18 is located atthe distal end of the piston rod 17. The pressure foot 18 is preferablymade of two separate parts which are snapped together around a distalend portion of the piston rod 17. The pressure foot 18 is disposed toabut the proximal face of the piston 7. The piston rod 17 is movable ina distal direction by means of a drive device, thereby pushing thepiston 7 to move axially within the cartridge 6 in the distal directionfor medication delivery. A first thread 15 is formed at the distal endof the piston rod 17 (first threaded section 15). A second thread 16 isformed at the proximal end of the piston rod 17 (second threaded section16). The first thread 15 and the second thread 16 are oppositelydisposed. Preferably at least one of the first and second threads 15, 16is a multi-start thread, most preferably both are two-start threads.

The drive device comprises a drive sleeve 19 which extends about thepiston rod 17. The drive sleeve 19 is generally cylindrical. The drivesleeve 19 is provided at a distal end with a radially extending flange20. A helical groove (thread) 21 extends along the internal surface ofthe drive sleeve 19. The second thread 16 of the piston rod 17 isadapted to work within the helical groove 21 of the drive sleeve 19.

A shoulder 22A and an extension 22B are formed at the proximal end ofthe drive sleeve 19. The extension 22B has reduced inner and outerdiameters in comparison to the remainder of the drive sleeve 19. Aproximal end of the extension 22B is provided with a radially outwardlydirected flange 23.

A clutch 24 is disposed about the drive sleeve 19, between the drivesleeve 19 and an end stop 28 (described below). The clutch 24 is locatedadjacent the proximal end of the drive sleeve 19. The clutch 24 isgenerally cylindrical and is provided at the distal end with a series ofcircumferentially directed saw teeth 29. Each saw tooth comprises alongitudinally directed surface and an inclined surface. Towards theproximal end of the clutch 24 there is located a radially inwardlydirected flange 30. The flange 30 of the clutch 24 is disposed betweenthe shoulder 22A of the drive sleeve 19 and the radially outwardlydirected flange 23 of the extension 22B. The proximal end of the clutch24 is provided with a plurality of saw teeth 31. The clutch 24 is keyedto the drive sleeve 19 by way of splines (not shown) to prevent rotationbetween the clutch 24 and the drive sleeve 19. The clutch 24 is providedwith a plurality of flexible arms 32 (not shown) that engage a pluralityof splines on an interior surface of a dose dial sleeve 27 (describedbelow).

A clutch plate 25 and a biasing means 26 are located between the distalend of the clutch 24 and the proximal face of the radially extendingflange 20 of the drive sleeve 19. In the illustrated embodiment, thebiasing means 26 is a spring. The proximal face of the clutch plate 25is provided with a series of circumferentially directed saw teeth 33.The clutch plate 25 is secured against rotation with respect to thehousing 3. The saw teeth 33 of the clutch plate 25 interact with the sawteeth 29 at the distal end of the clutch 24 during dose setting(described below).

An end stop 28 is disposed about the drive sleeve 19, between the drivesleeve 19 and the dose dial sleeve 27. The end stop 28 is securedagainst rotation with respect to the housing 3 and is free to moveaxially with respect to the housing 3. At the distal end of the end stop28 a radially extending flange 34 is provided designed to engage withspline features (not shown) on an interior surface of the housing 3. Inthe illustrated embodiment, the external surface of the end stop 28 isprovided with a helical groove (thread) that extends the full length ofthe end stop 28. The helical groove (thread) is engaged with a threadedinsert 53 of the dose dial sleeve 27. An interior surface of the endstop 28 is provided with a number of spline features (not shown). Theclutch plate 25 is engaged with these spline features and therebysecured against rotation with respect to the housing 3

A dose dial sleeve 27 is provided between the clutch 24 and the housing3. A helical groove (thread) 41 is provided about an outer surface ofthe dose dial sleeve 27. The housing 3 is provided with a helical rib(thread) 42, adapted to be seated in the helical groove (thread) 41 ofthe dose dial sleeve 27. In the illustrated embodiment, the helical rib(thread) 42 is formed on an interior surface of an insert 43. Thethreaded insert 43 is secured against rotation and axial movement withrespect to the housing 3. The helical rib 42 extends for a single sweepof the inner surface of the insert 43. A proximal end of the dose dialsleeve 27 is provided with an inwardly directed flange in the form of anumber of radially extending members 45.

The housing 3 is further provided with a window 40 (not shown) throughwhich a part of the outer surface of the dose dial sleeve 27 may beseen. A visual indication of the dose that may be dialed is provided onthe outer surface of the dose dial sleeve 27. The window 40 convenientlyonly allows a visual indication of the dose currently dialed to beviewed. The window can be designed such that it allows an enlargedvisual indication of the dose currently dialled to be viewed by actingas a magnifying lens. Preferably the window 40 is filled with atransparent polymer. Most preferably the window 40 is part of an insertof the housing 3 which is made by two component injection moulding,wherein a section with a dark polymer surrounds a section with atransparent polymer. The insert is immovably fixed to the housing, e.g.by means of an adhesive tape.

The threaded insert 43 of the housing 3 is provided with a series ofradial stop features 55, 56 (not shown). A distal end of the dose dialsleeve 27 is provided with a plurality of stop features 44 (not shown)which abut the stop features 56 of the insert 43 to prevent the dosedial sleeve 27 from being wound out of the housing 3 any further when amaximum dose has been set.

A dose dial grip 46 is disposed about an outer surface of the proximalend of the dose dial sleeve 27. An outer diameter of the dose dial grip46 preferably corresponds to the outer diameter of the housing 3. Thedose dial grip 46 is secured to the dose dial sleeve 27 to preventmovement therebetween. The dose dial grip 46 is provided with centralopening 47. An annular recess 48, located in the proximal end of thedose dial grip 46, extends around the opening 47.

A button 49 is provided at the proximal end of the medication deliverydevice 1. In the illustrated embodiment of instant invention, the button49 is of generally ‘T’ section, with a stem 50. The button 49 ispreferably free to rotate with respect to the housing 3. Preferably thebutton 49 contains a washer (not shown) made of a friction reducingmaterial (e.g. a friction modified polymer material) in order to reducethe friction between the button and dose dial grip 46 during dosedelivery. The stem 50 of the button 49 extends through the centralopening 47 in the dose dial grip 46 and through the inner diameter ofthe extension 22B of the drive sleeve 19. The stem 50 of the button 49is retained for limited axial movement in the drive sleeve 19 and theclutch 24. In the illustrated embodiment, a head 51 of the button 49 isgenerally circular. A skirt 52 depends from a periphery of the head 51.The skirt 52 is adapted to be seated in the annular recess 48 of thedose dial grip 46.

An internal surface at the distal end of the dose dial sleeve 27 isprovided with a helical thread (not shown). In the illustratedembodiment, the helical thread of the dose dial sleeve 27 is provided onan internal surface of the threaded insert 53. The insert 53 is retainedwithin the dose dial sleeve 27 by means of an end cap 54 secured to thedistal end of the dose dial sleeve 27. The end cap 54 is secured againstboth rotational and axial movement with respect to the dose dial sleeve27. The helical groove (thread) of the end stop 28 is engaged with thethreaded insert 53 of the dose dial sleeve 27.

The medication delivery device 1 further comprises nut means 11 which isa reset element and which has a series of face teeth 12 on a distalsurface and a threaded circular opening 13. The first thread 15 of thepiston rod 17 extends through and is threadedly engaged with thethreaded circular opening 13 of the nut means 11. The nut means 11 isprevented from axial movement in the distal and/or proximal directionwith respect to the housing 3, e.g. in the proximal direction by meansof a web 57 within the housing 3. The web 57 can be a separate componentor can be formed as part of the housing 3. In the devices shown in FIGS.1 a to 1 c the nut means 11 is in a operational state in which the nutmeans 11 is prevented from rotation with respect to the housing 3 bymeans of a locking means 9 and therefore prevents proximal movement ofthe piston rod 17 during dose setting and dose delivery.

In the illustrated embodiment, the medication delivery device 1 isfurther provided with a locking means 9. The locking means 9 is securedagainst rotational movement with respect to the housing 3, but thelocking means 9 is free for limited axial movement with respect to thehousing 3 when the housing 3 is engaged with or disengaged from thecartridge holder 2. The locking means 9 is provided on a proximalsurface with a series of face teeth 10 for engaging the face teeth 12 ofthe nut means 11. A biasing means 14, in the form of a spring, isprovided between the proximal face of the locking means 9 and a web 57within the housing.

In the shown embodiments according to FIGS. 1 a to 1 c the cartridgeholder 2 (medication receptacle) comprises actuation means 70 with ramps71, the inclined surfaces of the ramps 71 interacting with inclinedsurfaces 72 of the locking means 9 when the cartridge holder 2 is beingconnected with the housing 3 (described later with respect to FIGS. 2 ato 2 c and 3). By this interaction the locking means 9 is moved intoengagement with the nut means 11. The actuation means 70 thereby bringsthe nut means 11 in the operational state. This interaction will bedescribed in detail below.

Accordingly, when the cartridge holder 2 (medication receptacle) isengaged with the distal end of the housing 3 the reset element 11 is inthe operational state and when the cartridge holder 2 (medicationreceptacle) is disengaged from the distal end of the housing 3 the resetelement 11 is in a resetting state

In the operational state the reset element 11 is prevented from rotationwith respect to the housing 3, the piston rod 17 being prevented frommoving in a proximal direction, and in the resetting state the resetelement 11 is allowed to rotate with respect to the housing 3, themedication delivery device being resettable by rotating the piston rod17 in a second rotational direction and moving the piston rod 17 in theproximal direction.

Operation of the medication delivery device 1 in accordance with thepresent invention will now be described.

To dial a dose a user rotates the dose dial grip 46, thereby rotatingthe dose dial sleeve 27. During dose dialling the clutch 24 is engagedwith the dose dial sleeve 27 via the saw teeth 31 at the proximal end ofthe clutch 24. As the clutch 24 is engaged with the rotating dose dialsleeve 27, the clutch 24 and the drive sleeve 19 rotate with the dosedial sleeve 27 because of the splined engagement of the clutch 24 andthe drive sleeve 19.

Audible and tactile feedback of the dose being dialled is provided bythe clutch plate 25 and the clutch 24. This feedback is provided by thesaw teeth 29 of the clutch 24 gliding over the saw teeth 33 of theclutch plate 25 during the rotational movement of the clutch 24 withrespect to the housing 3. During dose dialling, the clutch plate 25 ispushed axially towards the proximal end of the device by the biasingmeans 26, thus ensuring that the saw teeth 29 and 33 of clutch plate 25and clutch 24 maintain contact. As the clutch plate 25 is securedagainst rotation by spline features on the interior surface of the endstop 28, which is secured against rotation with respect to the housing,the clutch 24 rotates relative to the clutch plate 25 during dosesetting. Due to the profile of the saw teeth 29 and 33, preferablytriangular, the saw teeth 29 of the clutch 24 are able to glide over thesaw teeth 33 of the clutch plate 25 as the clutch 24 rotates.Preferably, the ratio of the angular spacing of the saw teeth 29 of theclutch 24 and the saw teeth 33 of the clutch plate 25 is such that eachtooth pitch corresponds to a conventional unit dose, or the like.

The dose dial sleeve 27 is wound out of the housing 3 (rotationalmovement and axial movement in the proximal direction) when a dose to bedispensed is increased because of its engagement with (insert 43 of) thehousing 3 via the threads 41, 42. The helical groove 41 of the dose dialsleeve 27 and the internal thread 21 of the drive sleeve 19 have thesame lead. This allows the dose dial sleeve 27 to extend from thehousing 3 and the drive sleeve 19 to climb along the second thread 16 ofthe piston rod 17 in the proximal direction at the same rate (rotationalmovement and axial movement in the proximal direction with respect tothe housing 3 and with respect to the piston rod 17).

At the limit of travel, a radial stop (not shown) on the dose dialsleeve 27 engages with a stop feature 56 provided on the insert 43 ofthe housing 3 to prevent further movement. During dose setting rotationof the piston rod 17 is prevented due to the opposing directions of thefirst and second threads 15, 16 on the piston rod 17, the first thread15 being engaged with the nut means 11 and the second thread 16 beingengaged with the drive sleeve 19.

The end stop 28 which is prevented from rotating with respect to thehousing 3, preferably by means of spline features (not shown), movesaxially towards the proximal end of the housing 3 when the dose dialsleeve 27 rotates and moves in the proximal direction during dosesetting. When a dose is set that can maximally be dispensed from thecartridge 6, the radially extending flange 34 abuts a radial stop means60 formed on the piston rod 17, preventing the end stop 28 from furtherproximal axial movement and both the dose dial sleeve 27 and the drivesleeve 19 from rotating further in the direction for setting a largerdose.

Should a user inadvertently dial beyond the desired dosage, themedication delivery device allows the dosage to be dialed down withoutdispense of medicinal product from the cartridge 6. The dose dial grip46 is counter rotated for this purpose. This causes the system to act inreverse. The reverse rotation of the clutch 24 causes the saw teeth 29and 33 of the clutch 24 and the clutch plate 25 to ride over one anotherto create the clicks corresponding to dialled dose reduction. Preferablythe saw teeth 29 and 33 are so disposed that the circumferential extentof each saw tooth corresponds to a unit dose.

FIG. 1 a shows the medication delivery device in a state before a firstdose has been set. FIG. 1 b shows the medication delivery device 1according to FIG. 1 a in a state in which a dose has been set. The dosedial sleeve 27 is extending proximally from the housing 3.

When the desired dose has been dialled, the user may then dispense thisdose by depressing the button 49. This displaces the clutch 24 axiallytowards the distal end of the device with respect to the dose dialsleeve 27, thereby decoupling the clutch 24 from the dose dial sleeve27. However, the clutch 24 remains keyed in rotation to the drive sleeve19. Therefore the decoupling of the clutch 24 results in a decoupling ofthe dose dial sleeve 27 and the drive sleeve 19 The dose dial sleeve 27and associated dose dial grip 46 are free to rotate, guided by thehelical rib 42 of the insert 43 located in the helical groove 41 of thedose dial sleeve 27. During dose delivery the dose dial sleeve 27 iswound back into the housing 3 in the distal direction.

The pressure of the user on the button 49 further results in an axialmovement of the clutch 24 in the distal direction without rotation withrespect to the housing 3. The axial movement of the clutch 24 moves theclutch plate 25 distally against the force of the biasing means 26 untilthe clutch plate 25 abuts a shoulder on the drive sleeve 19 and theclutch 24 and clutch plate 25 are engaged such that relative rotationbetween the clutch 24 and the clutch plate 25 is prevented, thuspreventing rotation of the clutch 24 and the drive sleeve 19 withrespect to the housing 3 during dose delivery. As the clutch plate 25 issplined to the end stop 28 to prevent rotation of the clutch plate 25with respect to the housing 3, the clutch plate 25, the clutch 24 andthe drive sleeve 19 travel together distally but do not rotate.

The axial movement of the clutch 24 causes the drive sleeve 19 to moveaxially in the distal direction. The distal longitudinal axial movementof the drive sleeve 19 further causes (by means of the internal thread21 of the drive sleeve 19 and the second thread 16 of the piston rod 17)the piston rod 17 (first threaded section 15) to rotate and thus to windthrough the opening 13 in the nut means 11, thereby to advance thepiston 17 in the cartridge 6.

Once the dialled dose has been dispensed, the dose dial sleeve 27 isprevented from further rotation by a plurality of rotational stopfeatures (not shown) extending from the dose dial grip 46 engaging withstop features 55 located on the insert 43 of the housing 3. In theillustrated embodiment, the rotational stop features extend axially fromthe dose dial grip 46 and have an inclined end surface. The zeroposition is determined by the abutment of one of the axially extendingedges of the rotational stop features (not shown) with a correspondingstop 55 on the insert 43.

The rotational movement of the dose dial sleeve 27 during dose deliverycauses the end stop 28 to move axially in a distal direction back to itsinitial position within the housing 3.

FIG. 1 c shows the medication delivery device according to FIGS. 1 a and1 b after a dose has been dispensed. The piston rod 17 and the piston 7in the cartridge 6 have been advanced in the distal direction. The dosedial sleeve 27 and the end stop 28 are in their original position withrespect to the housing 3.

When the final dose has been dispensed, the spent cartridge 6 may beremoved and disposed of. To remove the cartridge 6, the cartridge holder2 is disengaged from the housing 3 by disengaging the first and secondengagement means 5, 4. Once the cartridge holder 2 is disengaged fromthe housing 3, the spent cartridge 6 can be removed from the cartridgeholder 2 and a new cartridge 6 can be placed in the cartridge holder 2.

For reusing the medication delivery device 1 it has to be reset bymoving the piston rod 17 proximally into its initial position. As longas the nut means 11 is in the operational state, the proximal movementof the piston rod 17 is prevented

-   -   due to the opposing directions of the first and second threads        15, 16 on the piston rod 17, the first thread 15 being engaged        with the non-rotatable nut means 11 and the second thread 16        being engaged with the drive sleeve 19 and    -   due to the clutch 24 which couples the drive sleeve 19 with the        dose dial sleeve 27 and therefore indirectly to the thread 42 of        the housing, the clutch 24 thereby forming part of stop means        which prevent proximal movement of the piston rod 17 in the        operational state.

Therefore the nut means 11 has to be brought into the resetting state,in which it is allowed to rotate with respect to the housing 3 so thatthe piston rod 17 can be moved in the proximal direction.

Disengagement of the cartridge holder 2 from the housing 3 causes thelocking means 9, under the force of the biasing means 14, to disengagefrom the nut means 11. The locking means 9 then does not preventrotation of the nut means 11 anymore. The nut means 11 is thus not inthe operational state anymore, it is in the resetting state. This allowsthe nut means 11 to rotate freely and therefore the piston rod 17 to bewound back up in the proximal direction.

In order to attach the cartridge holder 2 containing the new cartridge 6on the housing 3, the piston rod 17 has to be moved axially in theproximal direction. This proximal movement may be caused by the piston 7of the cartridge 6 abutting the end of the piston rod 17 and being movedproximally with respect to the housing 3 when the cartridge holder 2with the cartridge 6 is moved towards the housing 3 by the user.Alternatively the user may push the piston rod 17 in the proximaldirection e.g. by means of a finger and then attach the cartridge holder2 with cartridge 6 to the housing 3. As the nut means 11 (which isthreadedly engaged with the piston rod 17) is free to rotate withrespect to the housing 3 in the resetting state the piston rod 17 isfree to rotate and translate proximally until the locking means 9 andthe nut means 11 engage. The pushing back of the piston rod 17 by meansof the piston 7 of the new cartridge 6 which is pushed against thepressure foot 18 of the piston rod 17 has the advantage, that thepressure foot 18 of the piston rod 17 already abuts the piston 7 of thecartridge 6 when the device is reset. Therefore, the priming movement ofthe piston rod 17 (to remove air from the cartridge 6) can be very smalland the loss of medication due to priming thus be kept to a minimum.

The cartridge holder 2 containing the new cartridge 6 is engaged withthe housing 3 by moving the first and second engagement means 5, 4 intoengagement. As the cartridge holder 2 is moved into engagement with thehousing 3, the cartridge holder 2 first rotates and moves axially in aproximal direction, because the second engagement means 4 of the insert3A of the housing 3 moves along the threaded section of the firstengagement means 5 of the cartridge holder 2 until the second engagementmeans 4 reaches the annular groove section of the first engagement means5. The further movement of the second engagement means 4 in this annulargroove causes the cartridge holder 2 to rotate without moving axiallywith respect to the housing 3. The first and second engagement means 5,4 are therefore movable into engagement by a movement of the cartridgeholder 2 which ends in a rotational movement without axial movement ofthe actuation means 70 with respect to the housing 3. This furtherrotation of the cartridge holder 2 (without axial movement) causes theramps 71 of the actuation means 70 to glide along the inclined surfaces72 of the locking means 9. The locking means 9 is thereby moved axiallyin the proximal direction against the force of the biasing means 14until the face teeth 10 of the locking means 9 are engaged with the faceteeth 12 of the nut means 11, thereby bringing the nut means 11 (resetelement) in the operational state. In this position the nut means 11 issecured against axial movement and against rotation. In this operationalstate the piston rod 17 is prevented from rotation in one rotationaldirection and from axial movement in the proximal direction with respectto the housing 3 but is allowed to rotate in the other rotationaldirection and move axially in the distal direction with respect to thehousing 3 for medication delivery.

The pure rotational movement of the cartridge holder 2 and the actuationmeans 70 which moves the locking means 9 into engagement with the nutmeans 11 ends when snap-in features (not shown) of the cartridge holder2 and the insert 3A of the housing 3 engage. In this position theactuation means 70 holds the nut means 11 in the operational state.

The rotational movement (without axial movement) of the cartridge holder2 with respect to the housing 3 which moves the locking means 9 intoengagement with the nut means 11 has the advantage of not building upany pressure on the piston 7 of the cartridge 6 before the medicationdelivery device 1 is used.

Thus the dosing mechanism of the medication delivery device 1 accordingto the present invention is reset into a zero (or no dose delivered)position as indicated in FIG. 1 a.

FIGS. 2 a to 2 c show schematically an embodiment of an actuation meansinteracting with locking means in three different states according toone embodiment of the present invention.

FIG. 2 a shows a locking means 9 and an actuation means 70 before aninteraction takes place therebetween. In the shown embodiment theactuation means 70 is e.g. part of a medication receptacle (e.g. acartridge holder 2) of the medication delivery device. In the shownembodiment the component of the medication delivery device comprisingthe actuation means 70 further comprises first engagement means 5 forengaging with second engagement means 4 which are preferably part of thehousing of the medication delivery device or of an insert of thehousing. The first and second engagement means 5, 4 are designed suchthat for moving the two components which comprise the engagement means5, 4 (preferably the housing and the medication receptacle) intoengagement, the two components are first rotated and moved axially withrespect to each other (first step) and then only rotated without beingmoved axially with respect to each other (second step). The interactionbetween the actuation means 70 and the locking means 9 only takes placein this second step, when the two components (e.g. the medicationreceptacle and the housing) and therefore the actuation means 70 and thelocking means 9 only rotate with respect to each other. The lockingmeans 9 is preferably not rotatable with respect to the housing of themedication delivery device.

FIG. 2 a shows the actuation means 70 and the locking means 9 during thefirst step, when both rotation (arrow 35) and axial movement (arrow 36)therebetween take place. During this step the second engagement means 4moves along a first section of the first engagement means 5 which isrepresented by a thread 37. The distal end of the thread 37 merges intoa second section of the first engagement means 5 which is represented bya part of annular groove 38. In the schematic drawing this annulargroove 38 looks like a straight section because the drawing represents aview onto the outer surface of essentially cylindrical components.

The second engagement means 4 is at least one engaging element whichengages with the thread 37 and the annular groove 38. The shown engagingelement has the shape of a parallelogram.

In the shown embodiment the locking means 9 and the actuation means 70have special shapes for interacting. The actuation means comprises ramps71 with inclined surfaces for interacting with correspondingly inclinedsurfaces 39 of the locking means 9 which form triangular recesses 58.

In FIG. 2 a the combined axial movement 36 and rotation 35 of theactuation means 70 with respect to the locking means 9 results in theactuation means 70 approaching the locking means 9 until the actuationmeans 70 abuts the locking means 9 in a position in which the ramps 71are joined with the triangular recesses 58 of the locking means 9 asshown in FIG. 2 b. In this position the second engagement means 4 hasreached the point in which the thread 37 of the first engagement means 5merges into the annular groove 38 of the first engagement means 5. Thecombined axial movement 36 and rotation 35 of the actuation means 70with respect to the locking means 9 (first engagement step) now switchesover into a rotation 35 only of the actuation means 70 with respect tothe locking means 9 (second engagement step).

During this rotation the inclined surfaces of the ramps 71 and therecesses 58 glide along each other. This interaction of the actuationmeans 70 and the locking means 9 during the rotational movement withoutaxial movement drives the locking means 9 (which is non-rotatable withrespect to the (not shown) housing) axially in the proximal direction(arrow 59) as shown in FIG. 2 c. By this axial movement of the lockingmeans 9 (preferably against the force of a not shown biasing means) thelocking means 9 is driven into engagement with a (not shown) resetelement (e.g. a nut means), thereby bringing the reset element in aoperational state in which it prevents proximal movement of the pistonrod 17 during dose setting and medication delivery with the medicationdelivery device. The engagement of the locking means 9 and the resetelement can be established e.g. by interlocking of (not shown) faceteeth of the locking means 9 and the reset element.

FIG. 3 shows a cross-sectional enlarged view of a middle part of theembodiment according to FIGS. 1 a to 1 c showing the reset element ofthe medication delivery device in the operational state.

The cartridge holder 2 of the medication delivery device is attached tothe housing 3 of the medication delivery device by first engagementmeans 5 being engaged with second engagement means 4 (not shown). Thecartridge holder 2 comprises the first engagement means 5 and the insert3A of the housing 3 comprises the second engagement means 4. A two-partpressure foot 18 is mounted on the distal end of the piston rod 17 andabuts the piston 7 of the medication cartridge 6.

According to this embodiment the cartridge holder 2 comprises actuationmeans 70 which comprise ramps 71 with inclined surfaces for interactingwith correspondingly inclined surfaces 72 of locking means 9. Thelocking means 9 is engaged with a nut means 11 which is a reset elementin the operational state for preventing the proximal movement of thepiston rod 17. The tips of the ramps 71 of the actuation means 70 arepushed against the distal surface of the locking means 9, therebyholding the nut means 11 in the operational state. Face teeth 10 of thelocking means 9 are engaged with face teeth 12 of the nut means 11. Bythis engagement of the nut means 11 with the locking means 9 rotation ofthe nut means 11 with respect to the housing 3 is prevented. The nutmeans 11 is in threaded engagement with the first thread 15 of thepiston rod 17. By means of this threaded engagement and of theengagement of the (oppositely disposed) second thread 16 of the pistonrod 17 with the (not shown) drive sleeve, movement of the piston rod 17in the proximal direction is prevented as long as the nut element 11 isin the operational state. A biasing means 14 is provided to push the nutmeans 11 and the locking means 9 apart when the cartridge holder 2 isdisconnected from the housing 3 (not shown).

FIG. 4 shows schematically a different embodiment of the medicationdelivery device according to the present invention with a differentarrangement of actuation means and a reset element.

The actuation means 70 comprises ramps 71 and the medication receptacle2 comprises first engagement means 5 with threaded sections 37 and anannular groove 38. The reset element 11 has inclined surfaces 39 forinteraction with the ramps 71 of the actuation means 70. When theinclined surfaces of the ramps 71 and the reset element 11 abut andglide along one another during rotational movement of the actuationmeans 70 with respect to the housing 3 in the second engagement step,the reset element 11 is pushed against a locking means 9, face teeth 12of the reset element 11 thereby engaging with face teeth 10 of thelocking means 9. The locking means 9 of this embodiment is notnecessarily a separate component. It can also be part of the housing 3.

FIG. 5 shows another embodiment of a medication delivery deviceaccording to the invention.

The medication delivery device 1 according to FIG. 5 comprises acartridge holder 2 and a (exterior) housing 3. The distal end of thehousing 3 is provided with an insert 3B designed to engage with theproximal end of the cartridge holder 2. The insert 3B is secured againstrotation with respect to the housing 3 but is free to move axially withrespect to the housing 3. The extent of axial movement of the insert 3Bis limited by a retaining means 63 which is engaged with the housing 3and secured against both axial and rotational movement with respect tothe housing 3.

An inner surface of the insert 3B is provided with second engagementmeans 4. The second engagement means 4 could be any suitable means knownby a person skilled in the art, such as a bayonet, helical thread, orthe like. Preferably, the second engagement means 4 is a helical threadand corresponds to the first engagement means 5 at the proximal end ofthe cartridge holder 2, which is preferably also a helical thread.

In the shown embodiment of present invention, the proximal end of thecartridge holder 2 is further provided with an actuation means (notshown) designed to activate and lock a reset element (not shown) in anoperational state.

A biasing means 64 is provided between the proximal face of theretaining means 63 and the distal face of the insert 3B. The biasingmeans 64 may be manufactured from any suitable flexible material knownto a person skilled in the art, such as stainless steel, rubber, or thelike, and may be in any suitable form, such as a spring, spacer, or thelike. In the illustrated embodiment of instant invention, the biasingmeans 64 is a wave spring. The biasing means 64 is designed to ensurethat the insert 3B does not abut the retaining means 63 when thecartridge holder 2 is not engaged with the housing 3.

The further components of this medication delivery device will not bedescribed in detail, but are preferably similar to the components asdescribed with reference to FIGS. 1 a to 1 c.

Operation of the drug delivery device in accordance with the presentinvention will now be described.

The dialling of a dose and the dispensing of a dose can e.g. work in asimilar way as described with reference to FIGS. 1 a to 1 c.

When the final dose dispensed position is reached, the spent cartridgemay be removed and disposed of. To remove the cartridge, the cartridgeholder 2 is disengaged from the housing 3, preferably the cartridgeholder 2 is unscrewed from the housing 3, Once the cartridge holder 2 isdisengaged from the housing 3, the spent cartridge can be removed fromthe cartridge holder 2 and a new cartridge can be placed in thecartridge holder 2.

Disengagement of the cartridge holder 2 from the housing 3, causes the(not shown) reset element of the device to be moved out of itsoperational state, e.g. by a locking means under the force of a biasingmeans disengaging from the reset element. This for example allows thereset element to rotate freely and thus the piston rod to be moved inthe proximal direction for resetting the device.

With the cartridge holder 2 removed, the insert 3B is free to moveaxially in a proximal direction away from the distal end of the housing3 (away from the retaining means 63) for a limited distance by virtue ofthe force exerted by the biasing means 64.

In order to attach the cartridge holder 2 on the housing 3 the pistonrod is moved axially in the proximal direction with respect to thehousing 3. This proximal movement is caused by the piston of the newcartridge abutting the end of the piston rod and being moved proximallywith respect to the housing 3 when the cartridge holder 2 with thecartridge is moved towards the housing 3. As the reset element is notyet in the operational state the piston rod is free to translateproximally until the reset element is in the operational state, e.g.until locking means and the reset element engage. The pushing back ofthe piston rod by means of the piston of the new cartridge which ispushed against the pressure foot of the piston rod has the advantage,that the pressure foot of the piston rod already abuts the piston of thecartridge when the device is reset. Therefore, the priming movement ofthe piston rod (to remove air from the cartridge) can be very small andthe loss of medication due to priming thus be kept to a minimum.

The cartridge holder 2 containing the new cartridge is then engaged withthe housing, preferably threadedly engaged. As the cartridge holder 2 ismoved into engagement with the housing 3, the first engagement means 5located at the proximal end of the cartridge holder 2 engages with thesecond engagement means of the insert 3B. The cartridge holder 2 isallowed to rotate and move axially in a proximal direction (firstengagement step) until stop means 65 (e.g. an annular outer rim) locatedon the cartridge holder 2 abuts the retaining means 63 The stop means 65prevent further axial movement of the cartridge holder 2 but allow thecartridge holder 2 to rotate (second engagement step). As the cartridgeholder 2 rotates further, the insert 3B is moved axially, against theforce of the biasing means 64, towards the distal end of the housing 3and therefore towards the retaining means 63.

This pure rotation of the cartridge holder 2 additionally causes theactivation means to bring the reset element into the operational state(not shown), e.g. by a locking means being moved axially in a proximaldirection against the force of a biasing means until the face teeth ofthe locking means are engaged with face teeth of the reset element

Thus the drive mechanism is reset into a zero (or no dose delivered)position

The rotational movement (without axial movement) of the cartridge holder2 which brings the reset element in the operational state has theadvantage of not building up any pressure on the piston of the cartridgebefore the medication delivery device 1 is used for the first time afterinserting a new cartridge.

Reference Numbers

-   1 medication delivery device-   2 cartridge holder-   3 housing-   3A insert of the housing-   3B insert of the housing-   4 second engagement means-   5 first engagement means-   6 cartridge-   7 piston-   8 engaging means-   9 locking means-   10 face teeth of locking means-   11 reset element/nut means-   12 face teeth of nut means-   13 opening of nut means-   14 biasing means-   15 first thread of piston rod-   16 second thread of piston rod-   17 piston rod-   18 pressure foot-   19 drive sleeve-   20 flange of drive sleeve-   21 internal thread of drive sleeve-   22A shoulder-   22B extension-   23 flange-   24 clutch-   25 clutch plate-   26 biasing means-   27 dose dial sleeve-   28 end stop-   29 saw teeth at distal end of clutch-   30 flange of clutch-   31 saw teeth at proximal end of clutch-   32 flexible arms-   33 saw teeth of clutch plate-   34 flange at distal end of end stop-   35 rotation-   36 axial movement-   37 thread-   38 annular groove-   39 inclined surfaces-   40 window-   41 outer helical thread of dose dial sleeve-   43 thread of insert of the housing-   44 stop features on dose dial sleeve-   45 radially extending members-   46 dose dial grip-   47 central opening of dose dial grip-   48 annular recess of dose dial grip-   49 button-   50 stem of button-   51 head of button-   52 skirt of button-   53 threaded insert of dose dial sleeve-   54 end cap-   55 stop features on insert 43-   56 stop features on insert 43-   57 web-   58 recesses-   59 proximal direction-   60 radial stop means on piston rod-   63 retaining means-   64 biasing means-   65 stop means-   70 actuation means-   71 ramps-   72 inclined surfaces

1. A medication delivery device comprising: a housing having a proximaland a distal end, a medication receptacle designed to be engaged withthe housing, a piston rod which is moveable in a distal direction formedication delivery and a drive device for rotating the piston rod in afirst rotational direction and thereby moving the piston rod in thedistal direction for medication delivery; wherein the piston rodcomprises two threaded sections, wherein a first threaded section isprovided for threaded engagement with a reset element and a secondthreaded section is provided for threaded engagement with the drivedevice and wherein the threads in the first and second threaded sectionsare oppositely disposed, wherein in an operational state the resetelement is prevented from rotation with respect to the housing, thepiston rod thereby being prevented from moving in a proximal direction,and in a resetting state the reset element is allowed to rotate withrespect to the housing, the medication delivery device being resettableby rotating the piston rod and the reset element in a second rotationaldirection and moving the piston rod in the proximal direction, whereinwhen the medication receptacle is engaged with the distal end of thehousing the reset element is in the operational state and when themedication receptacle is disengaged from the distal end of the housingthe reset element is in the resetting state.
 2. The medication deviceaccording to claim 1, wherein the medication receptacle is designed tobe engaged with the distal end of the housing by engagement of firstengagement means and second engagement means, the first engagement meansand the second engagement means being moveable into engagement by amovement of the medication receptacle which comprises a rotationalmovement without axial movement of the medication receptacle withrespect to the housing.
 3. The medication delivery device according toclaim 1, wherein the medication receptacle comprises an actuation meansfor bringing the reset element in the operational state.
 4. Themedication delivery device according to claim 3, wherein the first andsecond engagement means are designed such that when the medicationreceptacle and the housing are moved into engagement, the actuationmeans are first rotated and moved axially with respect to the housingand are thereafter rotated without being moved axially, the actuationmeans thereby bringing the reset element in the operational state. 5.The medication delivery device according to claim 2, wherein themedication receptacle or an insert of the medication receptaclecomprises the first engagement means and that the housing or an insertof the housing comprises the second engagement means.
 6. The medicationdelivery device according to claim 2, wherein the first engagement meansis a thread of the medication receptacle and the second engagement meansis an engaging element of the housing or of an insert of the housing forengagement with the thread of the medication receptacle, wherein thedistal end of the thread of the medication receptacle merges into aannular groove such that the medication receptacle is engaged with thehousing by first rotating and moving proximally with respect to thehousing and then only rotating with respect to the housing.
 7. Themedication delivery device according to claim 2, wherein the distal endof the housing is provided with an insert comprising the secondengagement means designed to engage with the first engagement means atthe proximal end of the medication receptacle, the insert being securedagainst rotation but being free to move axially with respect to thehousing, wherein distal axial movement of the insert is limited by aretaining means.
 8. The medication delivery device according to claim 7,wherein the insert of the housing comprises an inner thread as a secondengagement means for engaging a first engagement means which is an outerthread at the proximal end of the medication receptacle, the medicationreceptacle being rotated and moved axially with respect to the insertand the housing in a first step for engaging the medication receptaclewith the housing and the medication receptacle being rotated while axialmovement of the medication receptacle is prevented with respect to thehousing in a second step for engaging the medication receptacle with thehousing, the insert being moved in the distal direction by the rotationof the medication receptacle during the second step.
 9. The medicationdelivery device according to claim 1, wherein the reset element is a nutmeans threadedly engaged with an external thread of the piston rod. 10.The medication delivery device according to claim 1, wherein the drivedevice comprises a drive sleeve and the second threaded section of thepiston rod is provided for threaded engagement with the drive sleeve.11. The medication delivery device according to claim 10, wherein thedrive sleeve is engaged with the piston rod for driving the piston rodin the distal direction during medication delivery, the drive sleevebeing moved axially and being prevented from rotation with respect tothe housing during medication delivery, thereby causing axial movementand rotation of the piston rod.
 12. The medication delivery deviceaccording to claim 10, comprising a stop means, the stop means beingdesigned such that during dose setting the drive sleeve is allowed tomove axially and rotate with respect to the housing while the drivesleeve is not allowed to move axially without rotation with respect tothe housing and during dose delivery rotation of the drive sleeve withrespect to the housing is not allowed while the drive sleeve is allowedto move axially in the distal direction without rotation with respect tothe housing.
 13. The medication delivery device according to claim 12,wherein the stop means comprises a clutch means which is non-rotatablyengaged with the drive sleeve.
 14. The medication delivery deviceaccording to claim 10, comprising a dosing mechanism which includes thepiston rod and the drive device, the dosing mechanism furthercomprising: a dose dial sleeve having a helical thread engaged with ahelical thread of the housing, the drive sleeve being releasably coupledwith the dose dial sleeve and a clutch means located between the dosedial sleeve and the drive sleeve, wherein, a) when the dose dial sleeveand the drive sleeve are coupled, both are allowed to rotate withrespect to the housing, and b) when the dose dial sleeve and the drivesleeve are de-coupled, rotation of the dose dial sleeve with respect tothe housing is allowed, whilst rotation of the drive sleeve with respectto the housing is not allowed and axial movement of the drive sleeve isallowed in the distal direction thereby transferring a force in thedistal direction to the piston rod.
 15. The medication delivery deviceaccording to claim 1, wherein the medication delivery device comprises alocking means which is non-rotatable with respect to the housing andwhich is engaged with the reset element in the operational state,thereby locking the reset element for preventing rotation of the resetelement with respect to the housing.
 16. The medication delivery deviceaccording to claim 15, wherein the reset element is a nut means which isthreadedly engaged with the piston rod and which is engaged with thelocking means in the operational state.
 17. The medication deliverydevice according to claim 15, wherein locking means and the resetelement comprise face teeth which interlock when the locking means andthe reset element are engaged in the operational state.
 18. Themedication delivery device according to claim 15, wherein the lockingmeans and the reset element disengage under the force of a biasing meanswhen the medication receptacle is disengaged from the housing.
 19. Themedication delivery device according to claim 15, wherein when themedication receptacle is disengaged from the housing, the locking meansand the reset element are disengaged, whereby the reset element is freeto rotate with respect to the housing in the resetting state.
 20. Themedication delivery device according to claim 1, wherein the medicationreceptacle is a cartridge holder which is designed to receive acartridge filled with medication.
 21. The medication delivery deviceaccording to any of claim 1, wherein the medication receptacle and thehousing are provided with snap-in features by means of which themedication receptacle and the housing are held in releasable engagement.22. The medication delivery device according to claim 1, wherein in thefirst threaded section the piston rod has a thread with a first pitchand in the second threaded section the piston rod has a thread with asecond pitch, wherein the first pitch is smaller than the second pitch.23. The medication delivery device according to claim 1 which is apen-type device.
 24. The medication delivery device according to claim 1which is an injector-type device.
 25. The medication delivery deviceaccording to claim 1, wherein medication delivery device comprises aneedle.